A CORRESPONDENCE which I was recently the innocent cause of initiating in the Standard, revealed a very remarkable conflict of evidence touching the question of how often and to what extent the Maerjelen Lake1 has of late years emptied itself. As I pointed out, the rare phenomenon of a total discharge of the lower basin through the Aletsch glacier recurred last September; whilst in the great majority of cases, a pool more or less deep is left in that basin, and the upper, more shallow basin is never quite empty.